Sonnō jōi

The Sonnō jōi movement was a political philosophy and social movement in Japan which advocated revering the Emperor, proscribing Christianity, and expelling foreigners from the islands. It became a rallying cry for enemies of the Tokugawa Shogunate, and the movement indirectly caused the Boshin War uprising against the pro-foreigner shogunate.

History
"Sonnō jōi" is the Japanese phrase for "Revere the emperor, expel the barbarians". The movement had originally focused on eradicating the new religion of Christianity upon its arrival in Japan in the late 16th and early 17th centuries, but the Kanagawa Convention of 1854 gave the term a new meaning. The Tokugawa Shogunate broke the national seclusion policy of Japan by opening the islands to trade with the United States and other western countries, and Japanese farmers and peasants became poor due to the influx of foreign merchants and the exodus of Japanese goods to the West. The Choshu Domain and Satsuma Domain both rebelled against the government due to its betrayal of the Japanese people, and the Japanese shelled foreign shipping off Shimonoseki while also assassinating shogunate officials and westerners. The  Sonnō jōi movement would not last long, however, as the start of the Boshin War in 1864 meant that the Choshu, Satsuma, and other pro-Emperor domains required foreign support to overthrow the Tokugawa Shogunate. The Emperor made peace with the United Kingdom, and the former xenophobic rebels would instead purchase Western guns and be given Western uniforms and training.